A plan to dramatically expand the numbers of possible Web addresses — by adding more than 1,000 new domains such as ".buy," ".casino" and ".gay" — could cause widespread disruption to Internet operations, say some industry officials.

Efforts to augment existing domains such as ".com" and ".gov" have been under way for several years and are entering a critical new phase as industry officials meet at an international conference that began Sunday in Durban, South Africa. By the end of summer, the new domains could be going live at a pace of 20 or more each week.

The plan has touched off a scramble among investors eager to gain control of the virgin Internet real estate, potentially worth billions of dollars in annual licensing fees. However, a vocal group of critics is calling the speed and scale of the expansion reckless, given its possible impact on the Internet's global infrastructure, which relies on interactions among computer networks owned by companies, universities and individual users.